Yeah, you would think that rain water running off roofing tiles might pick up contaminants, but if that's happening, it's never affected my fish. I've spawned corydoras paleatus, albino aeneus, laser green aneus, sterbai, and Brochis splendens in rain water from my 15 year old roof, and it's never seemed to bother them. Also a really fussy, fragile native, Enneacanthus chaetodon. I tried it on the discus, and it didn't seem to bother them either (although I gave it up after awhile, as it didn't seem to be making any difference, so I went back to tap.)
With oak leaves, I just picked them up from my backyard, rinsed them a little, then threw them in the tank. Again, it didn't seem to bother the chaetodon, but I've never tried them with any other species.
The other trick to soften water is to use peat moss (not peat humus.) I'm told the trick is to boil it before adding it to a filter bag. I tried it once, years ago, but never found any difference.
If you've got really difficult tap water to work with (like I do) and can't set up some sort of rainwater collection barrel or bucket, then you might want to invest in an RO system.
Sonny: My deck is pretty small to give it a 50 g drum. It would seem that the sediment from old roofing tile could be bad for fish...
Pat: On cichlid-forum Blair, the fellow who writes about oak leaves says.... only get leaves that have already fallen as they have less tanin. Also, you have to boil them...which would tank care of your concern about contamination.
Later,
Marge
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